1. Field of the Invention
This invention relates to a process and device for monitoring the position of an electric window, roof or door of a vehicle, and particularly an automobile.
It is particularly advantageous for applications in electrical control systems for vehicle windows, and control systems for opening roofs, sliding doors, etc.
2. Description of Related Art
In this system, conventionally it is considered that the position of the door, window or roof for which the displacement is being monitored is a linear function of the angular position of the rotor of the electric actuating motor.
However, it has been found that determinations of window, roof and door positions used in systems known in the past have not been reliable.
This is why sensors are usually provided in window winding mechanisms that are independent from the sensors provided to monitor rotation of the rotor of the electric motor and that are used to detect when the window reaches its limit stop.
One purpose of this invention is to overcome this disadvantage.
Consequently, the invention proposes a process for determining the position of a vehicle (particularly an automobile) door, roof or window, and particularly a window, according to which the angular position of the rotor of the electric motor actuating this window or door is determined, and the position of the window or door is calculated as a function of the said angular position, characterized in that the position of the door, window or roof is calculated by correcting the theoretical position that depends on the angular position by a term taking account of the stiffness of the mechanical transmission between the door, window or roof and the electric motor.
The position determined with this type of process is much more reliable than previously known means of determining positions.
It is found that, particularly for rack type window winding systems but and also for twisted cable window winding systems, the elasticity of the drive system between the motor rotor and the door, window or roof may be significant. The processing proposed by the invention compensates for this elasticity.
Advantageously, the correction term depends on the motor power supply current.
In one preferred embodiment, the position X of the door, window or roof is estimated using the following equation, which will need to be factored:
X=Rc.[xcex8xe2x88x92K(I)]
where:
Rc is the dynamic ratio of the mechanical transmission.
I is the current consumed in the DC motor.
K is the mechanical stiffness function.
The function K is preferably a linear function of I.
The invention also proposes a device to determine the position of a door, window or roof of a vehicle (particularly an automobile) comprising means of determining the angular position of the rotor of the electric motor actuating this door, window or roof and means of calculating the position of the door, window or roof as a function of the said angular position, characterized in that the said means embody the process mentioned above.
It also proposes a device for controlling an electric motor causing a displacement of a door, window or roof of an automobile vehicle, characterized in that it comprises a device of the type mentioned above.
Furthermore, the invention proposes an electric window winder for a vehicle, particularly an automobile, comprising at least one carriage that supports the window and that is driven in displacement by an electric motor, characterized in that it comprises such a control device.